linux-kernel - Please, put 64-bit counter per task and incr.by.one each ctxt switch.

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Message-ID: <998d0e4a0802231908h37978d07wa5379d5c01b2c2ee@mail.gmail.com>
Date:	Sun, 24 Feb 2008 04:08:38 +0100
From:	"J.C. Pizarro" <jcpiza@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>
Subject: Please, put 64-bit counter per task and incr.by.one each ctxt switch.

Hello,

We will need 64 bit counters of the slow context switches,
  one counter for each new created task (e.g. u64 ctxt_switch_counts;)

We will only need them during the lifetime of the tasks.

To increment by +1 the task's 64 bit counter (it's fast)
  each one slow context switch.

*kernel/sched.c:
void context_switch(...) { ... } # incr. +1 here.
void wake_up_new_task(...) { ... } # ->ctxt_switch_counts = 0ULL;

*include/linux/sched.h:
struct task_struct { ... } # add 64-bit (u64 ctxt_switch_counts;) here.

Please, do it and we can do it better than CFS fair scheduler.

I will explain your later why of it.

   O:)
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